The advantages of using a masking film in the coating industry to control unwanted application of coating media to selected metal and other surfaces have long been recognized.
Such advantages include, but are not limited to, coating cost reduction, for example, by using thin, low viscosity film-producing materials which are easily applied, e.g. by dipping or spraying, and which repel adhesion of applied coatings but which are readily removed after the coating operation has been completed.
A major problem which has been encountered with use of prior art masking films for dip coating processes is the tendency for highly viscous petroleum products-containing films to wash off during vigorous dip coating cycles, with consequent contamination of the coating product. Such wash-off effect can be eliminated by increasing the viscosity of the masking film; however, this also increases resistance of the film to removal after coating. Solvents which aid in removing low viscosity films also tend to remove the desired protective coatings. Examples of prior art masking films and their shortcomings include:
______________________________________ Wax must be applied at comparatively high temperature; must make contact with the surface to be masked by brushing; difficult to remove without covering other parts of the product being treated. Plating dries hard; is plastic-like; mask material flows into small holes, forming nipples which break off during revoval, causing holes to remain plugged; material becomes lodged in deep blind bushing bores. Solder used by the electronics industry to mask Mask electronic boards; generally painted on, but washes off with water; once paint is applied over the top of this masking material it seals in the masking which then is difficult or impossible to remove. ______________________________________